1. Field of the Invention
The present invention relates to a multi-speed transmission in which a plurality of drive gears and a plurality of driven gears are supported, in the state of being in constant mesh on a gear speed basis, respectively on gear shafts parallel to each other. More specifically, to a lubrication structure for a multi-speed transmission.
2. Description of Background Art
In the multi-speed transmission of the constant-mesh type, one group of gears of the drive gears and the driven gears are fixed on the gear shaft, the other group of gears are rotatably mounted on the gear shaft, and one of the rotatable gears which is engaged with the gear shaft is switched over by an engagement switch-over mechanism, thereby performing a shift.
A configuration is know wherein the engagement switch-over mechanism is a mechanism such that each of swing claw members supported on the gear shaft and swung has one end engaged with and disengaged from an engaging portion of an inner peripheral surface of the gear with a pin member being brought into contact with the other end of the swing claw member, and cam rods movably fitted respectively in a plurality of cam guide grooves formed by cutting in an axial direction along an inner peripheral surface of an inner cavity of the gear shaft operate the swing claw members through the pin members. A shift rod, disposed along the center axis of the inner cavity of the gear shaft, moves the cam rods. See, for example, Japanese Patent Application No. 2008-246752 previously applied for by the same applicant as the applicant of the present invention.
In the lubrication structure for a multi-speed transmission disclosed in Japanese Patent Application No. 2008-246752, a lubricating oil introduced into the inner cavity of the gear shaft via an introducing oil hole bored in an end portion of the gear shaft penetrates into gaps between cam guide grooves and cam rods movably fitted in the grooves to thereby pass in the gear shaft along the axial direction, and the oil is fed to the whole body of the engagement switch-over mechanism and over the entire length of the shift rod.
Since the gaps between the cam guide grooves and the cam rods are narrow, oil passage resistance is strong, and it is not easy to sufficiently lubricate the whole part of the engagement switch-over mechanism and over the entire length of the shift rod. Therefore, a large actuator has been needed for the lubrication.